Practice china-kaoyan-math-2 questions with answers and explanations.
The dot product is 3×2+4×1=10.
Rewrite the value using base 4: 256 = 4^4. Matching exponents gives x = 4.
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Use the circle-area formula A = πr². Substituting r = 4 gives A = π × 4² = 16π.
Percentage=(7/32)×100=21.88.
Subtract 10 from both sides and divide by 3: x = (43-10)/3 = 11.
By Vieta’s formula, the sum of the roots equals the coefficient 13.
Percentage=(6/31)×100=19.35.
Subtract 9 from both sides and divide by 2: x = (29-9)/2 = 10.
By Vieta’s formula, the sum of the roots equals the coefficient 10.
aₙ=a₁+(n−1)d=8+(11−1)×1=18.
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The sum is n(n+1)/2=10, so the mean is 10/4.
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There are 4 favourable outcomes out of 7 equally likely outcomes, so P(red)=4/7.
